The present invention is directed to a processing apparatus of the type which includes an upper tank and a lower tank for holding processing fluid and a narrow processing chamber located between the tanks through which a sheet of photosensitive material is advanced for processing of latent images on the material. Processing fluid is delivered to opposite sides of the photosensitive material from each of the tanks for forming a fluid layer on each side of the photosensitive material. A return drain is provided on each side of the photosensitive material for removing and returning the processing fluid to the sump tank. Example of such devices are illustrated in U.S. Pat. No. 4,989,028; U.S. Pat. No. 4,994,840; and U.S. Pat. No. 5,059,997.Such devices are often referred to as fluid suspension processors.
In fluid suspension processors of the prior art it is important to maintain the photosensitive material suspended in the processing fluid in the narrow chamber. It has been found that excessive contact of the photosensitive material with the sides of the processing chamber results in numerous undesirable artifacts being produced on the photosensitive material. In this regard, the prior art teaches the providing of flat plates for forming the sides of the narrow processing chamber. The surface of the flat plates may have a plurality of diamond shaped projections which are raised a small distance above the flat plate to prevent the film from sticking to the surface of the flat plate. This solution has not been totally satisfactory. Applicants have found that certain patterns produce a flow pattern which has a tendency to pull the film toward the surface of flat plates such that artifacts are produced on the film.
The present invention is directed to solving the problems experienced in prior fluid suspension processors by providing a pattern on the plate plates that form the sides of the narrow processing chamber which minimizes the tendency of the film of being pulled toward the sides of the processing chamber and thereby minimize contact of the film with the sides of the plates.